Low Alcohol Beer by evaporation

RichBenn · 02-07-2012, 08:10 PM

I recently saw an article about creating a low alcohol beer by putting the finished beer into an oven at 180 degrees. The idea is, since alcohol boils at about 172, one could reduce the amount of alcohol in a beer.

As my fondness for IIPAs and other strong brews grows, my tolerance for alcohol is waning. So lowering the alcohol this way, unlike brewing a "lite" beer, would seem to be a technique that bears investigation. But there has to be some "gotchas". And I don't really understand the chemistry:

1. How long would it take to reduce the alcohol significantly?
2. At 180 degrees, what is likely to happen to the hop oils? I've read of people adding all the flavor hops at flameout, then delaying cool down in order to get good hop flavor.
3. Is there a relationship between the various hop oils to the quantity of remaining alcohol?
4. I would think aromatics could be re-added by dry hopping in the keg. Thoughts?

Anyone ever tried this?

Rich

ConnorPPrice · 02-07-2012, 08:18 PM

Why not just reduce the grain bill?

**jester5120** · 02-07-2012, 08:19 PM

Only thing i might be able to answer is question 4. Dry hopping shouldn't be an option after alcohol is removed because hop oils are only heat or alcohol soluable. The only possibility ,and i'm not sure if this is what you were suggesting or if you were talking about at the original brew session, but it would be to add hops towards the end of the cook in the oven. That should pull aroma and flavor just like flameout hops

**jester5120** · 02-07-2012, 08:20 PM

Quote:

Originally Posted by ConnorPPrice

Why not just reduce the grain bill?

The original article was about low to no alcohol beers. It was about the idea of making a drinkable N/A beer. lowering the grain bill would compromise malt flavor

nefarious_1_ · 02-07-2012, 08:24 PM

I think this could work, but you'd lose beer in the process. While a lot of alcohol would evaporate, you'd also lose some water along with it which could lead to some unbalanced flavors in the resulting liquid. Unless you somehow adjusted the recipe accordingly. Maybe you could brew the recipe with the final volume in mind, but there's no way of telling what it will taste like without sacrificing a few batches first.

ConnorPPrice · 02-07-2012, 08:25 PM

Quote:

Originally Posted by jester5120

The original article was about low to no alcohol beers. It was about the idea of making a drinkable N/A beer. lowering the grain bill would compromise malt flavor

My mistake, I misread the OP. I thought this was looking for a relatively small reduction in alcohol to bring a beer more into session territory.

RichBenn · 02-07-2012, 10:40 PM

Quote:

Originally Posted by jester5120

Only thing i might be able to answer is question 4. Dry hopping shouldn't be an option after alcohol is removed because hop oils are only heat or alcohol soluable. The only possibility ,and i'm not sure if this is what you were suggesting or if you were talking about at the original brew session, but it would be to add hops towards the end of the cook in the oven. That should pull aroma and flavor just like flameout hops

I was suggesting "maybe" doing flavoring hops while removing alcohol, although I'm not sure it's necessary. The article seemed to think one would lose all the flavor and aroma at 180 degrees. That doesn't seem right to me, judging from how you can get some flavor from FWH. As I understand it, by letting the hops steep in the wort prior to the boil, the volatile oils and resins release, giving them more time to oxidize to more soluble compounds. Thus a greater percentage are retained during the boil. So....

For the aroma, I find MUCH more aroma doing a dry hop than a late hop, which is why I dry hop in the keg. I wasn't planning a "no alcohol" beer, so it would still work, I think.

Quote:

Originally Posted by nefarious_1_

I think this could work, but you'd lose beer in the process. While a lot of alcohol would evaporate, you'd also lose some water along with it which could lead to some unbalanced flavors in the resulting liquid. Unless you somehow adjusted the recipe accordingly. Maybe you could brew the recipe with the final volume in mind, but there's no way of telling what it will taste like without sacrificing a few batches first.

I hadn't thought of that, thanks. May just pull a gallon off a future batch just to see. Carb it up and give it a try.

**jester5120** · 02-08-2012, 01:18 AM

yeah if there's still alcohol then dry hopping should work. I didn't think of this until just now but I think a lot of what gets rid of aroma is the violent boil so 180 I think would be fine. I know the reason they tell you not to dry hop in primary is because the movement of co2 kicks out all the aroma. I would think the same principle probly applies to the boil

**remilard** · 02-08-2012, 01:39 AM

Quote:

Originally Posted by RichBenn

I recently saw an article about creating a low alcohol beer by putting the finished beer into an oven at 180 degrees. The idea is, since alcohol boils at about 172, one could reduce the amount of alcohol in a beer.

As my fondness for IIPAs and other strong brews grows, my tolerance for alcohol is waning. So lowering the alcohol this way, unlike brewing a "lite" beer, would seem to be a technique that bears investigation. But there has to be some "gotchas". And I don't really understand the chemistry:

1. How long would it take to reduce the alcohol significantly?
2. At 180 degrees, what is likely to happen to the hop oils? I've read of people adding all the flavor hops at flameout, then delaying cool down in order to get good hop flavor.
3. Is there a relationship between the various hop oils to the quantity of remaining alcohol?
4. I would think aromatics could be re-added by dry hopping in the keg. Thoughts?

Anyone ever tried this?

Rich

1. Nobody has ever done anything like this and verified success by directly measuring the remaining alcohol and decreased the alcohol by more than 50%. People who say it works just assume it works and never verify.

2. The hop oils are extremely volatile, heat some IIPA and your nose will tell you what is happening to the hop oils.

3. There is more ethanol than hop oil in an IIPA by orders of magnitude. You will destroy the hop character trying to get a third or half of the alcohol out.

4. Sure.

I would just make a San Diego Session Ale type beer (think Stone Levitation) if I wanted a 4% beer with IIPA like aroma. I think what you propose is a lot of work for a mediocre result.

**ajdelange** · 02-08-2012, 03:12 AM

Problem with this method is that the mole fraction of EtOH is so low. In a 6% ABV beer it is only 2%. At 82 °C (180 °F) the vapor pressure of EtOH over a 6% beer is 0.02*884 = 17.7. At the same temp. the vapor pressure of water is 0.98*389 = 381 mmHg. Thus for every ethanol molecule driven off 381/18 = 21 molecules of water escape. And, of course, as the alcohol concentration goes down the ratio becomes even less favorable. This is why a column is used in distillation and I guess you could use a column to just get rid of the alcohol - i.e. don't condense the vapors coming out of the column. The heat would still ruin the beer.

The "best" low alcohol beers are apparently made using dialysis to separate out the alcohol. Have you ever had one you liked?